Considering the rapid expansion of the use of cellular phones, increasing demand for access to the Internet, and business use of fiber optic links, there is convincing evidence of a continuing, increasing need to expand the capacity of telecommunications systems. As telecommunications systems expand there is also a need to upgrade essential equipment, such as telephone switching equipment, by replacing copper conductors of older installations with fiber optic signal transmission media. Fiber optics technology offers the superior bandwidth capability that is needed to handle the explosive increase in today's signal traffic.
Replacement of copper conductors by optical fibers has a direct effect upon the backplanes of switching equipment. The use of optical fiber on backplanes presents a unique set of problems including problems of optical fiber alignment and maintaining the cleanliness of optical fiber surfaces. One issue of alignment affects optimal positioning of daughter card fiber optic connectors and receiving connectors located on the backplane. Misalignment of optical fiber ends may cause attenuation of light signals passing through a connection zone between optical fibers. Optical fiber surface cleanliness becomes a problem when exposed ends of optical fibers reside in relatively inaccessible locations within the backplane. The presence of obscuring coatings of dirt particles at the interface between connected optical fibers impedes the passage of light. In the case of single mode fiber products, for example, the working diameter of the fiber is <10 microns and even a small dust particle could cause significant loss in signal.
It is known that the connecting surfaces of optical fibers should be maintained in a highly clean condition, free from contamination. Common causes of contamination include dust, finger oil, skin flakes, and the like. Some contaminants may be easily removed with a lintless wipe or by directing a jet of clean compressed gas towards loose particles to displace them from the surface of the optical fiber. More resistant contaminants such as skin oil require solvent cleaners that may be applied as a pressurized liquid spray. U.S. Pat. No. 4,733,428 describes a liquid spray cleaning tool adapted to clean optical surfaces for which access is difficult. The cleaning tool includes a injector which directs a cleaning liquid, and then a drying gas, under pressure towards the optical surface. An evacuation jacket removes cleaning fluids after application. The tool has a neck to fit onto an optical tip associated with an optical fiber.
Other methods for cleaning optical fiber surfaces include dry methods, as well as wet cleaning methods. Such methods include the use of a solvent rinse, compressed gas, and physical contact of optical fiber ends that may be contained in the ferrules of optical fiber connectors. U.S. Pat. Nos. 5,836,031, 5,956,793, 6,006,768, and U.S. Pat. No. 6,125,227 address a device for cleaning an optical fiber involving the deposit of a cleaning substance on a surface to be cleaned, particularly an optical surface such as a surface of an optical fiber. Description is given of application of both wet and dry substances. The cleaning device is selectively positionable for cleaning the tips of optical fibers which have been installed in a connector, such as a plug or a receptacle. A cleaning device includes a tool body having either a cleaning fluid or substantially dry cleaning media therein, such as a strip of adhesive tape. The adhesive tape may be in the form of a roll on a supply spool. Alternate designs are presented in which the cleaning media is not located in the tool body, but is manually applied to the fibers. Previously described methods are effective primarily when the optical fiber surface, requiring cleaning, is readily accessible.
Removal of contaminants becomes more difficult when optical fibers, that require cleaning, occupy a relatively inaccessible location such as a backplane buried inside a narrow slot through a switch card cage, at distances of sixteen inches or more. The inconvenience of removing optical fibers from backplanes, once installed, establishes the need for tools and techniques with which to accomplish remote cleaning of optical fiber surfaces during access from the front of a switch card cage. Fabric or paper tipped rods, described in U.S. Pat. Nos. 4,637,089 and 6,047,716 and UK Patent Application GB 2,349,070, may be used to reach into housings for optical fiber connectors. U.S. Pat. No. 6,209,162 also addresses this problem using a system for cleaning the end of a ferrule of a fiber optic connector mounted on a backplane of a chassis adapted for receiving a printed circuit board having a mating connector mateable with the fiber optic connector. A dummy circuit board is receivable by the chassis to replace the actual printed circuit board. A cleaner, mounted on the dummy circuit board, cleans the end of the ferrule of the fiber optic connector during insertion of the dummy board in a card slot. This solution brings with it the requirement for a custom fabricated dummy circuit board according to connector type, the dimensions of any structure containing a fiber optic surface and its position on the backplane. Also, the method uses a strip of material moving only in one direction without providing a scrubbing action.
A need exists for relatively simple, universal tools and processes to facilitate cleaning of relatively inaccessible optical fiber surfaces for optimum transmission of light signals.